Cytochrome cM Is Probably a Membrane Protein Similar to the C Subunit of the Bacterial Nitric Oxide Reductase

Cytochrome c(M) was first described in 1994 and its sequence has been found in the genome of manifold cyanobacterial species ever since. Numerous studies have been carried out with the purpose of determining its function, but none of them has given place to conclusive results so far. Many of these studies are based on the assumption that cytochrome c(M) is a soluble protein located in the thylakoid lumen of cyanobacteria. In this work, we have reevaluated the sequence of cytochrome c(M), with our results showing that its most probable 3D structure is strongly similar to that of the C subunit of the bacterial nitric oxide reductase. The potential presence of an alpha-helix tail, which could locate this protein in the thylakoid membrane, further supports this hypothesis, thus providing a new, unexpected role for this redox protein.

Automated summary

Cytochrome c(M) was first described in 1994 and its sequence has been found in the genome of many cyanobacterial species. Recent research suggests that its 3D structure is similar to the C subunit of bacterial nitric oxide reductase, potentially locating it in the thylakoid membrane and giving it a new role.